Debating life beyond Earth

In the June 6 issue, PAW reported that astrophysics professor Edwin Turner and researcher David Spiegel have concluded that “scientists’ excitement about the possibility of extraterrestrial life [is] fueled by a very unscientific component: optimism” (Campus Notebook). Just because life arose here, they say, we shouldn’t assume that it has arisen anywhere else. 

This brought back memories of an intellectual highlight of my undergraduate years, a debate in McCosh between two giants, Carl Sagan of Cornell and Freeman Dyson of the Institute for Advanced Study. Although the date is fuzzy — I’d guess it was 1974 — the details remain clear. Sagan, the world-famous, charismatic space junkie, argued that in a universe of “billions and billions” of stars (his widely parodied phrase), it is highly improbable that there is only one planet like ours. Surely the universe is teeming with life. Dyson, a towering intellectual with a decidedly low-key manner, contended that Sagan and his supporters made an appealing argument but one that was devoid of supporting evidence. 

At the end of the evening Dyson ­conceded that Sagan was the superior debater, and he came to admire Sagan’s work to promote the exploration of space. Still, half a lifetime before Turner and Spiegel, he reminded us that the existence of life beyond Earth was merely a hypothetical based on hope. Although Sagan died some years ago, I’d love to hear Dyson’s thoughts on the subject now.